Polymerizable composition solutions are useful as components of optically anisotropic bodies. Optically anisotropic bodies are applied to various liquid crystal displays as, for example, retardation films (films), retardation patterned films, and homogeneously aligned liquid crystal films. Retardation films are obtained by applying a polymerizable composition solution to a substrate and heating the polymerizable composition solution or curing a polymerizable composition through irradiation with active energy rays while the polymerizable composition solution is aligned by, for example, an alignment film.
In general, a polymerizable composition solution to be applied is used with a polymerizable composition dissolved in an organic solvent. This requires a drying process for removing the solvent by, for example, performing heating after application of the polymerizable composition solution to a substrate. After the organic solvent is removed by the drying process, a polymerizable liquid crystal compound in the polymerizable composition needs to be aligned on the substrate. It is necessary to align the polymerizable liquid crystal compound well with no defects in a wider temperature range for a long time because there are various processes for obtaining a retardation film.
A composition containing a (meth)acrylate compound has been proposed as an example of a polymerizable liquid crystal composition with good alignment properties, but the composition lacks sufficient alignment properties (PTL 1). A polymerizable liquid crystal compound with an azine backbone and a composition containing the polymerizable liquid crystal compound have been disclosed (PTL 2). PTL 2, however, discloses only the alignment properties of the polymerizable liquid crystal composition helically aligned with respect to a substrate. The alignment properties of the polymerizable liquid crystal composition that is horizontally aligned with respect to the substrate or vertically aligned with respect to the substrate are not known. The polymerizable liquid crystal compound with an azine backbone is unsuitable for retardation films because the compound is colored (PTL 2).
In addition, a method for aligning a polymerizable liquid crystal composition well may often involve improving the alignment properties of liquid crystal in an alignment film. For example, PTL 3 discloses an alignment film solution containing a hydrolysate of an alkoxysilane compound, a polymeric material having a hydroxyl group, and a cross-linking agent. PTL 4 discloses an alignment film containing a siloxane compound with an alkylsiloxane backbone.
As described above, there is a need to develop a polymerizable composition solution that allows a polymerizable compound in a polymerizable composition to be aligned well with no defects after application to a base and removal of a solvent by a drying process.